Microstrip GPS Circular Antenna for Terrestrial Transportation

Systems

IGNACIO ANTONIO HIDALGO-GARCIA1, MARIO REYES-AYALA1,

EDGAR ALEJANDRO ANDRADE-GONZALEZ1, SANDRA CHAVEZ-SANCHEZ2,

HILARIO TERRES-PEÑA2, JOSE IGNACIO VEGA-LUNA1, RENE RODRIGUEZ-RIVERA2

1Department of Electronics,

Metropolitan Autonomous University

San Pablo 420, Col. Nueva el Rosario, Azcapotzalco (ZIP 02128), Mexico City,

MEXICO

2Department of Energy,

Metropolitan Autonomous University,

San Pablo 420, Col. Nueva el Rosario, Azcapotzalco (ZIP 02128), Mexico City,

MEXICO

Abstract: - In this paper, the design, implementation, and evaluation of a microstrip circular antenna is

presented and analyzed. This antenna has two resonant frequencies, which are used in the Global Positioning

System (GPS). The antenna was built in a low-cost Printed Circuit Board (PCB) with a FR-4 substrate. The top

layer of the PCB includes two slots in the main circular patch, which normally is used in a single carrier

reception. The radiation pattern of the antenna shows a wide main lobe in the vertical axis, intending to obtain

line-of-sight communication links with five or more GPS satellites.

Key-Words: - Microstrip antenna, circular patch antenna, GPS, PCB, multi-band antenna, slot antenna, resonant

frequency.

Received: August 11, 2023. Revised: April 19, 2024. Accepted: May 8, 2024. Published: July 1, 2024.

1 Introduction

Global Positioning System (GPS) is a 32-satellite

constellation in a six-plane Medium Earth Orbit

(MEO) that gives time information and geolocation

around the globe. GPS is used by many

transportation systems anywhere, [1].

Fig. 1: Use of GPS in the urban environment

In the urban environment, the Line Of Sight

(LOS) path is frequently lost, as a consequence of

the presence of buildings or other large-size objects,

especially if the elevation angle of the link is lower

than 30 degrees, [2]. A very wide major lobe of the

antenna is placed on the top of a terrestrial vehicle

to achieve the necessary power in a GPS link budget

(Figure 1).

In this paper, a microstrip antenna with a circular

patch and two internal slots is proposed to enhance

the frequency response for two matching intervals

of GPS receivers. Each matching interval

corresponds to a resonant frequency (L1 and L2

carriers). L1 (1.57542 GHz) is used in civilian

mobile communications and L2 (1.22760 GHz) is

dedicated to military applications. L3, L4, and L5

are only related for military purposes and these

carriers are not employed in this paper.

The use of slots increases the number of resonant

frequencies producing a higher bandwidth in single

band antennas or multiband antennas, [3], [4], [5].

In this case, the size of the circular patch in the top

layer determines the resonant frequency of the L2

carrier, and the additional slots can stabilize the

frequency response and create a resonant frequency

for the L1 carrier.

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024

2 Problem Formulation

Using the typical circular patch approach presented

in [6], [7], [8], [9] and [10], we can determine the

geometry of the antenna with the equations (1) and

(2), that is shown in Figure 2.

  

󰇥  

󰇣󰇡

󰇢  󰇤󰇦 



(1)

   



(2)

Where fr is the resonant frequency for the L2

carrier;



r is the dielectric constant; is the thickness

of the PCB substrate; and, a is the radius of the

circular patch.

Fig. 2: Microstrip circular antenna

The impedance and line transmission for

matching the circular patch can be calculated using

the very well-known procedure for regular shape

microstrip antennas, [11], [12], [13], [14], [15], [16],

[17]. In this work, the circular shape was proposed

to obtain a more symmetric main lobe.

Table 1 summarizes the main parameters of the

antenna. The sizes of the slots were computed using

dipoles and rectangular microstrip antennas, [18],

[19], [20], [21].

Table 1. Antenna Model

Model Parameters

Size (mm)

Width of the Ground Plane

��

Length of the Ground Plane

��

The radius of the patch

�

32.3

Width of the feeder

��

0.3

Length of the feeder

��

Width of the first slot

��1

1.2

Length of the first slot

��1

36.4

Width of the second slot

��2

Length of the second slot

��2

Other shapes like triangles or bowtie antennas

have a larger bandwidth, but their main lobes are

asymmetric, [22]. The resulting geometry of the

antenna can be seen in the Figure 3.

Fig. 3: The final appearance of the antenna with the

insertion of two slots

3 Results

The antenna was simulated using the HFSS

software, which is a Finite Element Method (FEM)

that is one of the main choices in microstrip

antennas, [23].

Figure 4 illustrates the model that was simulated

with an FR-4 substrate. The orientation of the model

produces the main lobe in the vertical axis.

Fig. 4: Simulated model using HFSS

The carriers L1 and L2 of the GPS system were

obtained after the simulation of the S11 parameter

(Figure 5).

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024

Fig. 5: Return losses of the antenna obtained by

simulation

The numeric simulation results are shown in the

Figure 6, where antenna directivity is included, and

illustrated in the following figures (Table 2).

Table 2. Simulation Results

Parameter Description

Resonant frequency (L1)

1.5760 GHz

Resonant frequency (L2)

1.2360 GHz

Matching interval (L1)

1.9%

Matching Interval (L2)

2.6%

S11 (L1)

24.6054 dB

S11 (L2)

28.3271 dB

Bandwidth (L1)

300 MHz

Bandwidth (L1)

320 MHz

Antenna directivity

2.6003 dB

The insertion of the slots reduces the directivity,

which is illustrated in the Figure 6.

Fig. 6: Directivity pattern of the antenna (elevation

angle view)

The 3D antenna pattern shows the directivity of

the structure, which is approximately 2.6 dB (Figure

7).

Fig. 7: Tridimensional antenna pattern for the

directivity

After the simulation stage, the antenna was built

with a numerical tool with an accuracy of +/- 0.01

mm, which is necessary to get a good approximation

in comparison with HFSS results.

The antenna is displayed in Figure 8, where the

line transmission feeder of the antenna was designed

to match de circular patch with the measurement

equipment.

Fig. 8: Circular antenna built by CAD/CAM

methods

The same parameters obtained by simulation

were already measured using a Network Analyzer

(FieldFox). In the Figure 9, we can see a quite

similar plot presented before in simulations results.

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024

Fig. 9: Return losses obtained experimentally.

The same results were measured and saved in the

FieldFox and it is presented in Figure 10.

Fig. 10: Screen of the return losses obtained with a

FieldFox

The parameters obtained with the FieldFox are

summarized in Table 3, where matching intervals

are estimated using the markers shown in Figure 10.

Table 3. Frequency Response Results

Parameter Description

Resonant frequency (L1)

1.5672 GHz

Resonant frequency (L2)

1.2286 GHz

Matching interval (L1)

1.6%

Matching interval (L2)

2.1%

S11 (L1)

16.61 dB

S11 (L2)

14.84 dB

Bandwidth (L1)

260 MHz

Bandwidth (L2)

260 MHz

The last measurement was the antenna pattern,

which was obtained with a planar scanner that

measured the near field of the antenna. This

equipment is employed with a Personal Computer

(PC) and a FieldFox Network Analyzer (NA). The

far field of the antenna is computed by interpolation

in the PC.

The RFxpert scanner is provided by EMSCAN

and gives a very good approximation of the far field

in small and planar structures.

In Figure 11, the configuration of the equipment

is illustrated, where the communication is

performed by an ethernet or USB protocol.

Fig. 11: Measurement using a RFxpert by

EMSCAN

In Figure 12, we can see two azimuthal views 0º

(yellow) and 90º (red) plotted in a polar graph.

Fig. 12: 90º and 0º Azimuthal views of the antenna

pattern

The tridimensional antenna pattern is illustrated

in Figure 13, where it is clear the asymmetry of the

main lobe.

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024

Fig. 13: 3-D antenna pattern

4 Conclusion

In this work, a microstrip circular antenna for GPS

receivers was carried out. Analysis of regular shapes

of the microstrip antennas for mobile

communications was performed, and the insertion of

two slots was used to have two resonant frequencies

for L1 and L2 GPS most important carriers in

civilian applications. Other regular structures

modify the impedance, symmetry of the antenna

patterns, bandwidth, or size of the antenna, that is

the reason to use a circular patch, [24], [25], [26],

[27], [28], [29], [30], [31], [32], [33], [34].

The FR-4 substrate was selected to reduce the

price of the manufacturing process. It is necessary to

explain that this antenna is used for educational

purposes.

Right now we are employing this kind of antenna

with a regular method of manufacturing, and it is

important to say that the results are quite similar.

References:

[1] M. T. Torres, J. G. V. Dimas, G. U. Beltrán,

L. C. Villalobos, V. Grimalsky and S. V.

Koshevaya, “Simulation, Fabrication and

Tests of a GPS Antenna on the Roof-Top of

an Automobile”, Journal of Electromagnetic

Analysis and Applications, Vol. 4, No. 12, pp.

504-512, November 2012. DOI:

10.4236/jemaa.2012.412071.

[2] S. I. Chung, H. S. Lee and H. H. Lee, “A

Study on the In-orbit Environment of a GPS

Receiver for Low/Medium Altitude

Satellites”, IEEE International Conference on

Industrial Informatics, Daejeon, South-Korea,

pp. 694-699. DOI:

10.1109/INDIN.2008.4618190.

[3] C. A. Balanis, Antenna Theory, 3rd Edition,

New Jersey, John Wiley & Sons, 2016.

[4] J. L. Volakis, Antenna Engineering

Handbook, McGraw-Hill, 5th Edition, 2019.

[5] D. M. Pozar, Microwave Engineering, 4th

Edition, New Jersey, John Wiley & Sons,

2012.

[6] A. M. Abbosh and M. E. Bialkowski, "Design

of Ultrawideband Planar Monopole Antennas

of Circular and Elliptical Shape," IEEE

Transactions on Antennas and Propagation,

Vol. 56, No. 1, pp. 17-23, January 2008. DOI:

10.1109/TAP.2007.912946.

[7] A. Derneryd, "Analysis of the Microstrip Disk

Antenna Element," IEEE Transactions on

Antennas and Propagation, Vol. 27, No. 5,

pp. 660-664, September 1979. DOI:

10.1109/TAP.1979.1142159.

[8] K. Verma and Nasimuddin, "Simple

Expressions for the Directivity of a Circular

Microstrip Antenna," IEEE Antennas and

Propagation Magazine, Vol. 44, No. 5, pp.

91-95, October 2002. DOI:

10.1109/MAP.2002.1077780.

[9] R. E. Munson, “Conformal Microstrip

Antennas and Microstrip Phased Arrays,”

IEEE Transactions on Antennas and

Propagation, Vol. AP-22, No. 1, January

1974, pp. 74-78. DOI:

10.1109/TAP.1974.1140723.

[10] J. Q. Howell, “Microstrip Antennas,” IEEE

Transactions on Antennas and Propagation,

Vol. AP-23, No. 1, January 1975, pp. 90 - 93.

DOI: 10.1109/5.119568.

[11] D. S. Chang, “Analytical Theory of an

Unloaded Rectangular Microstrip Patch,”

IEEE Transactions on Antennas and

Propagation, Vol. AP-29, No. 1, January

1981, pp. 54-62. DOI:

10.1109/TAP.1981.1142533.

[12] J. R. James, P. S. Hall, C. Wood, A.

Henderson, “Some Recent Developments in

Microstrip Antenna Design,” IEEE

Transactions on Antennas and Propagation,

Vol. AP-29, No. 1, January 1981, pp. 124-

128. DOI: 10.1109/TAP.1981.1142527.

[13] W. F. Richards, Y. T. Lo, D. D. Harrison, “An

Improved Theory for Microstrip Antennas and

Applications,” IEEE Transactions on

Antennas and Propagation, Vol. AP-29, No.

1, January 1981, pp. 38-46. DOI:

10.1109/TAP.1981.1142524.

[14] S. S. Hong, Y. T. Lo, “Single-Element

Rectangular Microstrip Antenna for Dual-

Frequency Operation,” Electronics Letters,

Vol. 19, No. 8, August 1983, pp. 298-300.

DOI: 10.1049/el:19830208.

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024

[15] H. Pues and A. Van de Capelle, “Accurate

Transmission-Line Model for the Rectangular

Microstrip Antenna,” IEE Proceedings, Vol.

131, No. 6, December 1984, pp. 334-340.

DOI: 10.1049/ip-h-1.1984.0071.

[16] E. Chang, S. A. Long, W. F. Richards, “An

Experimental Investigation of Electrically

Thick Rectangular Microstrip Antennas,”

IEEE Transactions on Antennas and

Propagation, Vol. 34, No. 6, June 1986, pp.

767-772. DOI: 10.1109/TAP.1986.1143890.

[17] D. M. Pozar, “An Update on Microstrip

Antenna Theory and Design Including Some

Novel Feeding Techniques,” IEEE

Transactions on Antennas and Propagation

Society Newsletter, Vol. 28, October 1986, pp.

5-9. DOI: 10.1109/MAP.1986.27875.

[18] D. Edward, D. Rees, “A Broadband Printed

Dipole with Integrated Balun,” Microwave

Journal, 1987, pp. 339-344.

[19] J. S. Chen, K. L. Wong, “A Single-Layer

Dual-Frequency Rectangular Microstrip Patch

Antenna using a Single Probe Feed,”

Microwave and Optical Technology Letters,

Vol. 11, No. 2, February 1996, pp. 83-84.

doi.org/10.1002/(SICI)1098-

2760(19960205)11:2<83::AID-

MOP10>3.0.CO;2-8.

[20] K. W. Loi, S. Uysal, M. S. Leong, “Design of

a wideband microstrip bowtie patch antenna,”

IEE Proceedings – Microwaves Antennas and

Propagation, Vol. 145, No. 2, April 1998, pp.

137-140. DOI: 10.1049/ip-map:19981632.

[21] Y. W. Jang, “Broadband Cross-Shaped

Microstrip-Fed Slot Antenna,” Electronics

Letters, Vol. 36, No. 25, December 2000, pp.

2056-2057. DOI: 10.1049/el:20001477.

[22] Y. Tawk, K. Y. Kabalan, A. El-Hajj, C. G.

Christodoulou, J. Constantine, “A Simple

Multibeam Printed Bowtie Antenna,” IEEE

Antennas and Wireless Propagation Letters,

Vol.7, February 2008, pp. 57-560. DOI:

10.1109/LAWP.2008.2001027.

[23] ANSYS, [Online].

www.ansys.com/products/electronics/ansys-

hfss (Accessed Date: April 23, 2024).

[24] Y. Qian, W. R. Deal, N. Kaneda, T. Itoh, “A

Uniplanar Quasi-Yagi Antenna with Wide

Bandwidth and Low Mutual Coupling

Characteristics,” 1999 IEEE AP-S

International Symposium on Antennas and

Propagation, July 1999, Vol. 2, pp. 924-927,

Oralndo, Florida, USA. DOI:

10.1109/APS.1999.789463.

[25] N. Kaneda, W. R. Deal, Y. Qian, R.

Waterhouse, T. Itoh, “A Broad-Band Planar

Quasi-Yagi Antenna,” IEEE Transactions on

Antennas and Propagation, Vol. 50, No. 8,

August 2002, pp. 1158-1160. DOI:

10.1109/TAP.2002.801299.

[26] G. Zheng, A. A. Kishk, A. B. Yakovlev, A.

W. Glisson, “Simplified Feeding for a

Modified Printed Yagi Antenna,” 2003 IEEE

Antennas and Propagation Society

International Symposium, June 2003, pp. 934-

937, Columbus, Ohio, USA. DOI:

10.1109/APS.2003.1220063.

[27] M. Qudrat-E-Maula, L. Shafai, “Broadband

Rare Radiating Printed Dipole Antenna,”

2011 IEEE International Symposium on

Antennas and Propagation, July 2011, pp.

255-258, Spokane, Wyoming, USA. DOI:

10.1109/APS.2011.5996690.

[28] M. Qudrat-E-Maula, L. Shafai, “Size

Reduction of a Rear Radiating Microstrip Fed

Printed Dipole Antenna,” 2012 IEEE

International Symposium on Antennas and

Propagation, July 2012, pp. 1-2, Chicago,

Illinois, USA. DOI:

10.1109/APS.2012.6348736.

[29] M. Qudrat-E-Maula, L. Shafai, “Low-Cost,

Microstrip-Fed Printed Dipole for Prime

Focus Reflector Feed,” IEEE Transactions on

Antennas and Propagation, Vol. 60, No. 11,

November 2012, pp. 5428-5433. DOI:

10.1109/TAP.2012.2208170.

[30] M. Qudrat-E-Maula, L. Shafai, Z. A. Pour, “A

Corrugated Printed Dipole Antenna with

Equal Beamwidths,” IEEE Transactions on

Antennas and Propagation, Vol. 62, No. 3,

March 2014, pp. 1469-1474. DOI:

10.1109/TAP.2013.2295598.

[31] M. Qudrat-E-Maula, L. Shafai, “A Dual Band

Microstrip Dipole Antenna,” 2014 16th

International Symposium on Antenna

Technology and Applied Electromagnetics,

July 2014, pp. 1-2. Victoria, British

Columbia, Canada. DOI:

10.1109/ANTEM.2014.6887674.

[32] G. W. Hanson, D. P. Nyquist, “The RCS of a

Microstrip Dipole Deduced from an

Expansion of Pole Singularities,” IEEE

Transactions on Antennas and Propagation,

Vol. 41, No. 3, March 1993, pp. 376-379.

DOI: 10.1109/8.233121.

[33] C. Turkmen, Y. Bakirli, M. Secmen, “Printed

Quasi Yagi Antenna with Closely Spaced and

Thick Directors for Triple ISM-

Band/Wideband Applications at UHF,” 2018

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024

IEEE International Symposium on Antennas

and Propagation & USNC/URSI National

Radio Science Meeting, July 2018, pp. 677-

678, Boston, Massachusetts, USA. DOI:

10.1109/APUSNCURSINRSM.2018.8609205

[34] S. A. Alekseytsev, A. P. Gorbachev, “The

Novel Printed Dual-Band Quasi-Yagi

Antenna With End-Fed Dipole-Like Driver,”

IEEE Transactions on Antennas and

Propagation, Vol. 68, No. 5, May 2020, pp.

4088-4090. DOI:

10.1109/TAP.2019.2950837.

Contribution of Individual Authors to the

Creation of a Scientific Article (Ghostwriting

Policy)

- Ignacio Antonio Hidalgo García: Formal analysis,

investigation, methodology, writing – original

draft

- Mario Reyes-Ayala: Conceptualization,

investigation formal analysis, writing, review and

editing

- Edgar Alejandro Andrade-Gonzalez: Project

administration, resources, review, validation

- Sandra Chavez-Sanchez: Visualization, review

validation

- Rene Rodriguez-Rivera: Visualization, review

validation

- Hilario Terres-Peña: Supervision, validation,

review

- Jose Ignacio Vega-Luna: Validation, review

Sources of Funding for Research Presented in a

Scientific Article or Scientific Article Itself

This work was supported by the research project

EL002-18 at the Metropolitan Autonomous

University in Mexico City.

Conflict of Interest

The authors have no conflicts of interest to declare.

Creative Commons Attribution License 4.0

(Attribution 4.0 International, CC BY 4.0)

This article is published under the terms of the

Creative Commons Attribution License 4.0

https://creativecommons.org/licenses/by/4.0/deed.en

_US

WSEAS TRANSACTIONS on COMMUNICATIONS

DOI: 10.37394/23204.2024.23.2

Ignacio Antonio Hidalgo-Garcia,

Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez,

Sandra Chavez-Sanchez, Hilario Terres-Peña,

Jose Ignacio Vega-Luna, Rene Rodriguez-Rivera

E-ISSN: 2224-2864

Volume 23, 2024